I just bought a used 2004 Ford Taurus SES DOHC. Now the car can start normally. As said in the manual, I usually put the ignition switch to ON (position 4 in the manual), the electronic components begin to work and then I start the engine. However, when the switch is ON, there is a warning message "low oil pressure", and the oil light is on. But the message disappear after the engine is started, and the oil light is also turned off. I just had the engine oil been changed yesterday, the message still remained. So I'm wondering whether this kind of message is normal or not. Thank you very much.